Canon Camera

When looking at the Canon House what is the difference between fd and ef?

I am new to Digital Slr cameras and am looking to get a goal zoom .. I have a Canon Eos rebel xt. I have been looking on ebay and am not sure what would work w / my camera.

For starters, the lens products FD will not work on any EOS camera. All work on the EF-S EOS cameras, EF lenses only work on APS-C sensored DSLR …. If you own an EOS 35mm SLR or a 5D or 1D digital SLR, the EF-S lenses can damage the mirror